The six levels are an ancient method of traditional Chinese medicine that is based on the theory of six energy channels: Taiyang, Yangming, Shaoyang, Taiyin, Shaoyin, and Jueyin. The method first appeared early in history, in 25 BCE, and was expounded upon in many ancient Chinese texts. Some early Chinese texts that include references to the six levels include the “Shang han Iun” and “Wan Gan Wen Re Pain,” both books written about the disease process. The six levels are utilized to explain the nature and progression of pathogenic disease. They show how energy shortages, excesses, and blockages contribute to the onset of disease and overall energy imbalance.
The method purports that the clinical manifestations of disease are caused by pathogenic heat within the human system. The heat is said to be processed through four stages: wei (the outer defensive), qi (the inner defensive), yin (the nutrient stage), and xue (the blood stage. These body strata classifications help the practitioner to understand the severity and general location of pathologies, which help him or her to form a clinical diagnosis and treatment plan. Another, slightly different, interpretation of this aspect of the six levels says that there are only three areas in which to pinpoint pathogenesis: the lower, middle, and upper regions of the human body cavity.
The first level, that of Taiyang disease, is the level known as the generator of exterior syndromes. People experiencing Taiyang disease may have an aversion to cold, a light white tongue coating, and pain and rigidity in the neck. The next level, Yangming, is the level of diseases caused by exterior forces of cold and wind that transmit directly to the interior of the body; disease processes of the Yangming usually involve the intestines and stomach and can result in chronic constipation. The third level, Shaoyang, is responsible for diseases that have been caused by unrelieved Taiyang energy. People who are experiencing Shaoyang diseases may have vertigo, poor appetite, and a slippery white tongue coating.
The second set of the six levels begins with the Taiyin level. People who have these diseases are thought to be suffering from a pathogenic coldness condition, most likely due to delayed treatment of the first three levels. The fifth level is the Shaoyin level, which is characterized by diseases that result in listlessness, a feeble pulse, and overall pathogenic coolness. The last level, Jueyin, is characterized by either extreme heat or extreme cold diseases, which makes this last level the most complex and hardest to treat.